RFR: JDK-8285496: DocLint does not check for missing `@param` tags for type parameters on classes and interfaces

[Jonathan Gibbons]

Please review a trivial update for doclint, to check for `@param` tags for type parameters of classes and interfaces.

The bug was discovered recently, while making an update for record components, but this part of the fix was effectively blocked by the presence of missing tags in API documentation.

As well as a minor update to an existing test, the change has been tested by running `make docs`, `make docs-javase` and `make docs-reference`, all of which succeed without any warnings about missing tags.

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Commit messages:
 - JDK-8285496: DocLint does not check for missing `@param` tags for type parameters on classes and interfaces

Changes: https://git.openjdk.java.net/jdk/pull/8458/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8458&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285496
  Stats: 9 lines in 3 files changed: 6 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8458.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8458/head:pull/8458

PR: https://git.openjdk.java.net/jdk/pull/8458